1. Field of the Invention
The present invention relates to a mortise lock. In particular, the present invention relates to a mortise lock including two handles that can be returned to their original horizontal position.
2. Description of the Related Art
FIG. 1 of the drawings illustrates a conventional mortise lock comprising an inside handle assembly 1, an outside handle assembly 2, and a chassis 3 between the inside handle assembly 1 and the outside handle assembly 2. The chassis 3 is mounted in a mounting hole (not shown) of a door (not shown) and includes a plurality of bolts 31 and a mechanism for operating the bolts 31. The inside handle assembly 1 includes an inside handle 11 and an inside spindle 12 having an end received in a spindle hub 32b of the chassis 3. The outside handle assembly 2 includes an outside handle 21 and an outside spindle 22 having an end received in another spindle hub (not shown) of the chassis 3 that is aligned with the spindle hub 32b. When either handle 11, 21 is turned, the associated spindle 12, 22 and the associated spindle hub of the chassis 3 are turned to retract the bolts 31.
The inside handle assembly 1 further includes an inside spring package 15 mounted around the inside spindle 12 for returning the inside handle 11 to its original position (generally horizontal) when the inside handle 11 is turned and then released. The inside spring package 15 includes a spring seat 151, a collar 152 having a square hole 155 through which the inside spindle 12 extends, a spring 153 mounted to the spring seat 151, and a lid 154 for housing the spring 153 and the collar 152. When the inside handle 11 is turned, the inside spindle 12 and the collar 152 are turned. When the inside handle 11 is released, the inside handle 11 is returned to its original horizontal position under the action of the spring 153. The inner handle 11 further includes a threaded section 111 on an end thereof to which a sleeve 13 is mounted. The sleeve 13 includes an inner threading 131 for threadedly engaging with a stud 161 projecting from a side of a connecting member 16 that provides a support for two screws 17 that are engaged with two posts 27 of the outer handle assembly 2. An inside rose 14 is provided to house the inside spring package 15 and associated elements. Similarly, the outside handle assembly 2 further includes an outside spring package 25, a sleeve 23, a connecting member (not shown), and an outside rose 24 for returning the outside handle 21 to its horizontal position.
Installation of the sleeves 13, 23 to the end of the associated handles 11, 21 is troublesome. Further, the sleeves 13, 23 may be undesiredly turned together with the handles 11, 21 due to friction, causing loosening of the handles 11, 21. Further, the elements of the lock are apt to be damaged or permanently deformed by the torque applied to the handles 11, 21 (especially lever-type handles), adversely affecting retraction of the bolts 31.
Further, the handles 11, 21 are generally made from brass, which is relatively expensive. Processing of the threaded section 111 of the handles 11, 21 and the inner threading 131 of the sleeves 13, 23 is troublesome and expensive. Further, special tools are required for mounting the sleeves 13 and 23.